Violence and gore doesn't make a film, but making a movie of this type with a PG-13 rating is IMO just rank stupidity, and hints more at a cynical way of making money from hype rather than trying to make a good movie.
Take the Alien. Those horrible facehugger things catch you by the face and lay eggs in your throat. They gestate within a host, where upon it bursts from the chest cavity in a shower of blood. The alien itself as concentrated acid for blood, has claws and a tail like razors, and an inner mouth that punches through the skull of its victims, spattering brain matter everywhere.
And the Predator. An unprincipled hunter which kills its victims using extremely high powered or extremely sharp horrific weapons, then it fillets them or disembowels them, skins them, and hangs them up. Sometimes it may take the skull as a trophy (ripping it out the body along with a trailing length of spinal column), which it boils, scrapes the skin off with a sharp metal tool, and polishes.
How is ANY of this going to look in PG-13? The fact that the film won't be violent isn't what it will ruin it. The fact that it won't make any sense at all will be what does. Neither alien will be able to do what made it so famous in the other films. And nobody in the human cast will be able to respond in a realistic way to anything that's going on.
It is destined to be utter crap, not because the subject matter, not because the rating, but the two combined. It's like Reservoir Dogs II being made as a PG. It's awful. I wont' be going to see it. If I wanted to see a kid's movie I'd watch Spy Kids.
